Register language services in a dynamic registry

Author: ahoppen

Sources/InProcessClient/InProcessSourceKitLSPClient.swift

@@ -60,6 +60,7 @@ public final class InProcessSourceKitLSPClient: Sendable {
     self.server = SourceKitLSPServer(
       client: serverToClientConnection,
       toolchainRegistry: toolchainRegistry,
+      languageServerRegistry: LanguageServiceRegistry(),
       options: options,
       hooks: hooks,
       onExit: {

Sources/SKTestSupport/TestSourceKitLSPClient.swift

@@ -164,6 +164,7 @@ package final class TestSourceKitLSPClient: MessageHandler, Sendable {
     server = SourceKitLSPServer(
       client: serverToClientConnection,
       toolchainRegistry: toolchainRegistry,
+      languageServerRegistry: LanguageServiceRegistry(),
       options: options,
       hooks: hooks,
       onExit: {

Sources/SourceKitLSP/CMakeLists.txt

@@ -6,7 +6,7 @@ add_library(SourceKitLSP STATIC
   Hooks.swift
   IndexProgressManager.swift
   IndexStoreDB+MainFilesProvider.swift
-  LanguageServerType.swift
+  LanguageServiceRegistry.swift
   LanguageService.swift
   LogMessageNotification+representingStructureUsingEmojiPrefixIfNecessary.swift
   MessageHandlingDependencyTracker.swift

Sources/SourceKitLSP/LanguageServerType.swift

@@ -0,0 +1,43 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2014 - 2024 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See https://swift.org/LICENSE.txt for license information
+// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+//
+//===----------------------------------------------------------------------===//
+
+import IndexStoreDB
+import LanguageServerProtocol
+import SKLogging
+
+/// Registry in which conformers to `LanguageService` can be registered to server semantic functionality for a set of
+/// languages.
+package struct LanguageServiceRegistry {
+  private var byLanguage: [Language: LanguageService.Type] = [:]
+
+  package init() {
+    self.register(ClangLanguageService.self, for: [.c, .cpp, .objective_c, .objective_cpp])
+    self.register(SwiftLanguageService.self, for: [.swift])
+    self.register(DocumentationLanguageService.self, for: [.markdown, .tutorial])
+  }
+
+  private mutating func register(_ languageService: LanguageService.Type, for languages: [Language]) {
+    for language in languages {
+      if let existingLanguageService = byLanguage[language] {
+        logger.fault(
+          "Cannot register \(languageService) for \(language, privacy: .public) because \(existingLanguageService) is already registered"
+        )
+        continue
+      }
+      byLanguage[language] = languageService
+    }
+  }
+
+  func languageService(for language: Language) -> LanguageService.Type? {
+    return byLanguage[language]
+  }
+}

Sources/SourceKitLSP/LanguageServiceRegistry.swift

@@ -35,6 +35,14 @@ import DocCDocumentation
 /// Disambiguate LanguageServerProtocol.Language and IndexstoreDB.Language
 package typealias Language = LanguageServerProtocol.Language
 
+struct LanguageServiceIdentifier: Hashable {
+  private let identifier: String
+
+  init(type: LanguageService.Type) {
+    self.identifier = String(reflecting: type)
+  }
+}
+
 /// The SourceKit-LSP server.
 ///
 /// This is the client-facing language server implementation, providing indexing, multiple-toolchain
@@ -75,7 +83,9 @@ package actor SourceKitLSPServer {
 
   package var capabilityRegistry: CapabilityRegistry?
 
-  var languageServices: [LanguageServerType: [LanguageService]] = [:]
+  private let languageServiceRegistry: LanguageServiceRegistry
+
+  var languageServices: [LanguageServiceIdentifier: [LanguageService]] = [:]
 
   package let documentManager = DocumentManager()
 
@@ -160,11 +170,13 @@ package actor SourceKitLSPServer {
   package init(
     client: Connection,
     toolchainRegistry: ToolchainRegistry,
+    languageServerRegistry: LanguageServiceRegistry,
     options: SourceKitLSPOptions,
     hooks: Hooks,
     onExit: @escaping () -> Void = {}
   ) {
     self.toolchainRegistry = toolchainRegistry
+    self.languageServiceRegistry = languageServerRegistry
     self._options = ThreadSafeBox(initialValue: options)
     self.hooks = hooks
     self.onExit = onExit
@@ -450,11 +462,11 @@ package actor SourceKitLSPServer {
   /// If a language service of type `serverType` that can handle `workspace` using the given toolchain has already been
   /// started, return it, otherwise return `nil`.
   private func existingLanguageService(
-    _ serverType: LanguageServerType,
+    _ serverType: LanguageService.Type,
     toolchain: Toolchain,
     workspace: Workspace
   ) -> LanguageService? {
-    for languageService in languageServices[serverType, default: []] {
+    for languageService in languageServices[LanguageServiceIdentifier(type: serverType), default: []] {
       if languageService.canHandle(workspace: workspace, toolchain: toolchain) {
         return languageService
       }
@@ -467,7 +479,7 @@ package actor SourceKitLSPServer {
     _ language: Language,
     in workspace: Workspace
   ) async -> LanguageService? {
-    guard let serverType = LanguageServerType(language: language) else {
+    guard let serverType = languageServiceRegistry.languageService(for: language) else {
       logger.error("Unable to infer language server type for language '\(language)'")
       return nil
     }
@@ -478,7 +490,7 @@ package actor SourceKitLSPServer {
 
     // Start a new service.
     return await orLog("failed to start language service", level: .error) { [options = workspace.options, hooks] in
-      let service = try await serverType.serverType.init(
+      let service = try await serverType.init(
         sourceKitLSPServer: self,
         toolchain: toolchain,
         options: options,
@@ -538,7 +550,7 @@ package actor SourceKitLSPServer {
         return concurrentlyInitializedService
       }
 
-      languageServices[serverType, default: []].append(service)
+      languageServices[LanguageServiceIdentifier(type: serverType), default: []].append(service)
       return service
     }
   }

Sources/SourceKitLSP/SourceKitLSPServer.swift

@@ -294,6 +294,7 @@ struct SourceKitLSP: AsyncParsableCommand {
     let server = SourceKitLSPServer(
       client: clientConnection,
       toolchainRegistry: ToolchainRegistry(installPath: Bundle.main.bundleURL),
+      languageServerRegistry: LanguageServiceRegistry(),
       options: globalConfigurationOptions,
       hooks: Hooks(),
       onExit: {